题解 | #字符串加解密#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String plaintext = in.next();
        String ciphertext = in.next();
        System.out.println(encrypt(plaintext.toCharArray()));
        System.out.println(decrypt(ciphertext.toCharArray()));
    }

    static char[] encrypt(char[] charArray) {
        for (int i = 0; i < charArray.length; i++) {
            if (charArray[i] >= 'a' && charArray[i] <= 'z') {
                charArray[i] -= 'a';
                charArray[i] = (char) ((charArray[i] + 1) % 26);
                charArray[i] += 'A';
            } else if (charArray[i] >= 'A' && charArray[i] <= 'Z') {
                charArray[i] -= 'A';
                charArray[i] = (char) ((charArray[i] + 1) % 26);
                charArray[i] += 'a';
            } else if (charArray[i] >= '0' && charArray[i] <= '9') {
                charArray[i] -= '0';
                charArray[i] = (char) ((charArray[i] + 1) % 10);
                charArray[i] += '0';
            }
        }
        return charArray;
    }

    static char[] decrypt(char[] charArray) {
        for (int i = 0; i < charArray.length; i++) {
            if (charArray[i] >= 'a' && charArray[i] <= 'z') {
                charArray[i] -= 'a';
                charArray[i] = (char) ((charArray[i] + 25) % 26);
                charArray[i] += 'A';
            } else if (charArray[i] >= 'A' && charArray[i] <= 'Z') {
                charArray[i] -= 'A';
                charArray[i] = (char) ((charArray[i] + 25) % 26);
                charArray[i] += 'a';
            } else if (charArray[i] >= '0' && charArray[i] <= '9') {
                charArray[i] -= '0';
                charArray[i] = (char) ((charArray[i] + 9) % 10);
                charArray[i] += '0';
            }
        }
        return charArray;
    }
}

不使用特殊值，只使用字符值求解